1. Field of the Invention
The present invention relates to a method of cutting carbon nanotubes. More particularly, the invention is directed to a method of cutting carbon nanotubes which improves the dispersion properties of the carbon nanotubes by simplifying the structural change or surface modification of the carbon nanotubes, thereby enabling an active substance to be inserted into the inner walls of the carbon nanotubes and increasing catalyst support efficiency.
2. Description of the Related Art
Carbon nanotubes were first observed as a side product of a fullerene synthesis reaction. In general, carbon nanotubes consist of multiple layers (typically 2 to 50 layers) of smaller concentric carbon nanotubes capped at both ends. Such carbon nanotubes are formed from sheets of hexagonally or pentagonally arranged carbon atoms, and have hollow cores with diameters of up to 50 nm and lengths of 100 to 200 μm.
Carbon nanotubes can be produced in large scale by, for example, arc discharge, catalytic decomposition of hydrocarbons or laser ablation. Carbon nanotubes are known to have prominent mechanical and electrical properties such as electroconductivity, which is attributable to the unique crystalline structure and electron arrangement of the carbon nanotubes. These properties are a reason why carbon nanotubes are currently being heavily researched .
Carbon nanotubes can potentially be used in a variety of applications such as, for example, field emission, electrical and thermal conduction, catalyst support, hydrogen storage and molecular sieves. However, when used in applications such as catalyst support, hydrogen storage or molecular sieves, carbon nanotubes face dispersion difficulties due to van der Waals bonding attributable to characteristics of the one-dimensional structure of the carbon nanotubes. As a result, it has been difficult to efficiently utilize the large surface areas of carbon nanotubes. In order to overcome these problems, short carbon nanotubes having open ends have been used (i.e. production of short carbon nanotubes from long carbon nanotubes).
However, conventional methods of producing short carbon nanotubes, such as acid treatment, ball milling, etc., cause structural damage and surface damage to the carbon nanotubes, and result in a lesser yield of short carbon nanotubes. Since the production of short carbon nanotubes with good physical qualities is difficult and expensive, there is a need for a new, economical method of producing carbon nanotubes having higher conductivity.